Haitian Johnny Rivas (wearing necktie) organizes fellow Haitians who are farmworkers in the neighboring Dominican Republic. His group, Solidaridad Fronteriza, developed an identification system aimed at averting abuses by Dominican officials

Guayubín, Dominican Republic — The intense midafternoon sun is cooking the quiet town plaza here when Johnny Rivas returns on his motorbike, still wearing his oversized white suit.

He looks exhausted. Over the past few hours Mr. Rivas has emceed a workers' day celebration for Haitian immigrants, hosted a church ceremony, and shaken hundreds of hands.

He has sung along to both the Haitian and Dominican Republic's national anthems and has rented and returned 200-some folding chairs. And, most important, over and over he has given his pitch about identification badges – the central part of his effort to formalize the region's vast and marginalized Haitian workforce.

"I cannot be tired," he says with a smile. "There is still work to do."

Sure enough, he seems to perk up as he starts talking about the needs in one of the nearby bateyes, the ramshackle towns in the Dominican Republic where Haitian laborers live. Bateyes tend to be poor, with high unemployment.

In this agricultural northwest region of the country, Haitians also face another huge problem: documents, or, more accurately, the lack thereof.

"People who are undocumented, they're very vulnerable here," Rivas says. "Many of the Haitians who are here, they don't even have a birth certificate. This is why we took the initiative to give them the badges."

Many of the estimated 1 million Haitians who live in the Dominican Republic struggle to obtain official documents necessary to fully participate in society. In this land of sweeping banana fields and rustling sugar cane plantations, the threats facing undocumented immigrants are especially acute.

Thousands of Haitian immigrants – some legal, many not – perform the backbreaking manual labor that fuels the factories and farms, or fincas, here. Many are smuggled into the country. Others bribe border guards after they cross the Massacre River, the dividing line here between Haiti and the Dominican Republic.

They are typically low-paid, sometimes living and working in near-slavery conditions. Often they cannot get documents from the Haitian consulates here or are considered dysfunctional, and either don't have legal papers from the Dominican Republic or have their work visas held by their employers.

This makes them at risk for exploitation, Rivas and others say. Many workers tell stories of business owners who collude with immigration officers, setting up Haitians for mass deportation just before their payday. Others tell of roadblock officers who shake them down if they venture onto the main roads.

Without any way to prove their identity, they say, Haitians have no defense against predatory officials.

A few years ago, Rivas's organization, the Jesuit-run Solidaridad Fronteriza, came up with a plan. It decided to create its own identification badges, a way for the undocumented to document themselves.

Rivas and others began going town to town, interviewing workers to determine how long they've been in the Dominican Republic, where they work, how many children they have, their identification number in Haiti, and any other bits of information they could put on legitimate-looking badges.

"We must legalize the workers," says Father Rehino Martinex Breton, the director of Solidaridad Fronteriza, who has worked in the region for nearly four decades. "We propose that immigration officials allow people to circulate with the badge we give them. It has no legal authority, but a moral one."

Since the program started, Solidaridad has distributed more than 6,000 badges. Many have been arranged by Rivas.

Rivas is Haitian by birth, but has lived in the Dominican Republic for most of his life. He was a schoolteacher in Haiti, but here he worked, like most Haitians, in the fields. His employers fired him after they realized he was organizing other Haitians.

In 2003, impressed by what he saw the Jesuits doing to defend immigrant workers, he volunteered. Soon, he had a full-time job with Solidaridad. He was elected by the other workers as a group leader.

"He is a very well-known person," says Kelly Jean, a Haitian agricultural worker who paid a trafficker to help him sneak into the Dominican Republic in 2004. "He is a very helpful person, so he's very popular among the people."

Others seem to share Mr. Jean's view. When Rivas arrives at a grim collection of aluminum shacks, men and women gather around. Most show him that they have their badges hanging around their necks.

Area officials have started to recognize these IDs, they say, although they still have trouble when they travel farther away.

"Tell how you were shot here," one worker calls out to Rivas.

Rivas nods and explains that once, when he was having a meeting here, word came that a Dominican soldier was beating a Haitian man. Rivas rushed out into the street to break up the fight. The soldier fired his shotgun, hitting Rivas.

He shrugs off the incident. "I am not scared," Rivas says. "We have more important things to worry about. And with these badges, we are making a start."

•Travel for this story was funded by the Pulitzer Center on Crisis Reporting.